If you are a young adult or teenager, you can't live without Facebook. It's the first site I go to when I turn on my computer. I have even checked it on my mobile on planes and in toilets. Which should go some way toward explaining why Facebook topped Google as America's most visited site a fortnight ago.

Forget dates in the diary – Facebook is a one-stop events calendar. A friend once sent out beautiful hand-made invitations to her birthday party. "It's so quaint!" she cooed. Four days later the invites had been lost and no one could remember if the party was happening a week on Saturday or a month on Sunday.

Facebook has changed the way we approach relationships. You don't meet somebody at a party and hope you run into them again five months later. You add them to your "friends" list on the social networking site. A couple of years ago, I might have known about 30 people at university and had five close friends. Now I can keep in touch with hundreds.

The downside is that you have infinite access to the private lives of your friends. It's weird when you begin a story, only to have someone say, "I know, I saw the Facebook pictures." And it can lead to less-than-pleasant revelations about people you thought you knew. A close friend once offered to house-sit when my mother was out of town. Two weeks later, a photo album called "London FUNTIMES" appeared on the friend's profile. House-sitting now apparently includes inviting 10 people round to smoke a huge shisha pipe. Which explained the charred crater in the middle of my mum's cream carpet.

Even worse is the Facebook photobomb – when you turn up in the background of somebody else's photo doing something you shouldn't. A few years ago, you might have been an amusing but anonymous backdrop in a picture hidden in a photo album. Now, your friends immediately tag you as the girl pictured throwing up in the pint glass.

But it's not all bad news. You can at least vet new acquaintances to avoid those who join Facebook groups with "hilarious" titles such as "WTF is Alice doing in Wonderland? How did she get out of the kitchen?".

So if you're surprised that Facebook could get even more hits than Google, you clearly haven't been using it right. Either that, or you're still on Friends Reunited.